This invention relates, generally, to a method of treating at least the submergible surfaces of a fiberglass boat hull so as to repair, prevent or retard the formation of blisters thereon. For a number of years fiberglass has been extensively used for constructing boat hulls. Initially, fiberglass gained rapid acceptance as a preferred material for the construction of boat hulls because it was economical to use, was highly durable and resistant to damage, required only low maintenance, was attractive in appearance and was readily treated with anti-fouling materials. However, after boats with fiberglass hulls had been in use for several years, particularly those left in the water over long periods, it became evident that the fiberglass hulls were subject to the formation of blisters which, in addition to being unsightly, could, if left untreated, ultimately jeopardize the integrity of the fiberglass boat hulls.
It was soon determined that the blisters resulted from water penetrating the gelcoat on the exposed submergible surfaces of the fiberglass boat hulls on through to the underlying laminate. Thereafter, the water migrates into the fiberglass and pressure pockets form which result in the formation of the blisters between the gelcoat and the matte of the fiberglass. In some cases the blisters form in isolated or scattered areas and are relatively few in number with respect to the overall submergible surface. In other cases the blisters form throughout the entire submergible surfaces. In either case, if the blisters are left unattended water will continue to permeate and seep through the matte and, in some instances, into the woven roving, which is the structural portion of the fiberglass layup. Thus, while the blisters are initially objectionable for cosmetic reasons, they are the symptom of more serious problems to come, since, if the water permeation problem is not corrected, delamination of the fiberglass layers will occur.
Currently, there are essentially two methods used to repair fiberglass boat hulls on which blisters have formed. If the blisters are not extensive and if the water has not permeated the matte portion of the fiberglass, the blisters are usually ground off, the resulting "pot holes" or excised areas are filled with epoxy resin, and then faired to a smooth surface. Thereafter, an epoxy bottom coating that contains platelets as moisture barriers is applied over the repaired areas. A primer is then applied to the boat bottom which is then painted with anti-fouling paint. Rarely does this type of repair last very long. In most cases, if the repaired boat is used under the same conditions as before, the bottom will re-blister within a period of about two years and generally the re-blistering will then involve a larger area, or perhaps the entire bottom.
In the case of fiberglass boat hulls on which blisters have formed in large areas or perhaps over the entire bottom, the gelcoat protective barrier is taken off with a planer, or otherwise removed, down to the bare fiberglass matte. The bottom is then allowed to dry for a period ranging from several weeks to several months as may be required. When the fiberglass matte is dry, the entire bottom receives the following treatment:
a. Spots that have been ground out to get rid of moisture are filled with epoxy fairing compound and smoothed out to the bottom contour. PA1 b. After proper preparation, a clear epoxy coating is applied to serve as a sealant. PA1 c. After the sealant cures, several coats of epoxy base moisture barrier are applied to the bottom. Such epoxy moisture barrier generally consists of an epoxy resin with platelets suspended in it. By applying several coats, the platelets overlap one another and provide a moisture barrier.
The latter type of repair of the entire bottom of a boat is very costly, takes the boat out of use for an extended period and will impede the permeation of water for a period of only two to three years. Almost always, if the boat is used under the same conditions as before, the bottom re-blisters and the overall treatment of the bottom must be repeated.
The object of the invention, generally stated, is the provision of economical and practical methods of treating newly constructed fiberglass boat hulls and repairing fiberglass boat hulls on the bottoms or submergible surfaces on which blisters have formed, so as to prevent, retard and/or repair the formation of blisters.